1. Field of the Invention
The present invention relates to a method and a structure for supplying a heated medium into a resin material injection path before injecting a resin material at the time of secondary molding of a primary molded resin component in which the heated medium is supplied.
2. Description of the Related Art
In processing a hollow resin molded component, e.g. an intake manifold of an automotive vehicle, a primary molded component is secondary molded. In the process, a plurality of primary molded components, segmented by the primary molding, are set in a secondary molding die. These primary molded components are butted against each other and a resin material flow path is formed at the butt junction of the primary molded components. Then, a secondary molding resin material is injected into the flow path thus formed. In this way, an intake manifold can be integrally formed as a resin molded component.
In the case where the resin molded component is an intake manifold, the flow path is formed over a large distance in the primary molded component. If the secondary molding process is executed on the cooled and solidified primary molded component at room temperature, the secondary molding resin material injected is hardened so excessively that the problem is posed of a deteriorated deposition (joining after fusion) quality and a reduced deposition strength.
In the prior art, Japanese Unexamined Patent Publication No. 2003-245980 (Patent Document 1) discloses a method to solve the aforementioned problem and to improve the deposition strength by injecting a resin material after heating only the surface of the junction of the primary molded component to be coupled.
In this conventional method, the resin molded component is, for example, an intake manifold, and the junction of the primary molded components butted against each other in the secondary molding die is formed with a flow path to inject the secondary molding resin material around a pipe portion and a surge tank portion of the intake manifold. A first end of the intake manifold or, for example, one point of a part of the surge tank is formed with an inlet of a heated medium, and a second (the other) end or, for example, an end of one pipe portion is formed with a resin material inlet. Before injecting the resin material, the heated medium is supplied by way of the heated medium inlet. The heated medium is supplied over the entire periphery of the flow path and heats the surface of the junction. Once the heated medium comes to cover the whole peripheral surface of the flow path, the inflow of the heated medium is stopped, and the secondary molding resin material is injected into the heated flow path from the injection port.
As a result, the segmented primary molded components of a uniformly heated resin material can be coupled to each other, thereby preventing a reduction in deposition strength.
In the molding machine described Patent Document 1, however, if the heated medium supplied into the resin material flow path is a heated air, a hot air generator is arranged as a heated medium source. The hot air generator is often a commercially available air heater to supply a heated air to the forward end of a nozzle. The hot air blown from this air heater requires some length of time before reaching a steady temperature after the starting of the air heater. In the case where this variable hot air is supplied into the flow path of a molded component during this initial rising time, the temperature of the side wall in the path may be lower than a predetermined temperature in view of the fact that a steady heating temperature is not yet reached. This promotes the hardening of the resin material injected and reduces the deposition strength.
Therefore, it is desired to positively supply the heated medium, heated to a predetermined temperature, into the flow path of the molded component.